Interpenetrating network compositions and structures

ABSTRACT

Structure, composition and method in which a fiber reinforcement is impregnated with an interpenetrating network of a light cure resin and a thermosetting resin which are independently curable, enabling autobody component repair, electronic assembly bonding, etc. by selective cure first of one or the other resin, and the support against fluid flow of the uncured resin by the first cured resin.

REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 08/389,432filed on Feb. 14, 1995, now abandoned, which is a continuation of myapplication Ser. No. 07/824,583 filed Jan. 23, 1992, now abandoned.

FIELD OF THE INVENTION

This invention has to do with improved products and methods for autobodycomponent repair, improved products and methods for electronic assembly,and other applications, more generally with novel compositions and novelstructures comprising an interpenetrating network of separately curableresins which afford the opportunity to first cure one resin and therebyto maintain the other resin in place for subsequent cure to the finalproduct. In the autobody use of the present methods and products, acomposition of a light cure resin and a thermosetting resin, arranged inan interpenetrating network, is impregnated into a fiber reinforcement,such as a fiberglass mat to form a structure. The thermosetting resin iscured sufficiently to hold the light cure resin in place in the matstructure. The mat structure, sometimes referred to herein as a prepreg,slightly inwardly recessed, is used to bridge across the front side ofan opening circumscribing the damaged area of the autobody component,e.g a reinforced resin bumper, body panel, etc. The mat structure isexposed to light adequate to cure the light cure resin, stiffening themat structure and bonding the mat structure to the opening edge margin.Body filler is superimposed on the bridging mat structure and the massfinished for painting. Unlike any such autobody component repairpreviously used, this repair with the compositions and structures of thepresent invention is accomplished on the outside of the autobodycomponent panel, avoiding removal and/destruction of the existing bodycomponent panel, lessening cost and maximizing results for the carowner.

In a second highly commercial application, and one which demonstratesthe versatility of the invention compositions and structures, anelectronic assembly, i.e. the combination of conductive elements, iseffected with benefits in dimensional stability, by impregnating a matas before, and curing the light cure resin first to retain in place theuncured thermosetting resin (the reverse of the previously describedprocedure), to obtain a somewhat stiffened, easy to handle, lightlytacky structure. This structure can be cut to fit the footprint of anelectronic element to be bonded to another electronic element, e.g. acircuit board. The assembly is made with the mat sandwiched between theelectronic components and the thermosetting resin is then cured bondingthe elements together. The strength and precision of the structure andthe fixed dimensionality of the mat is of benefit in avoiding stressesin the assembly in subsequent thermal cycling situations.

These and other applications of the invention are benefitted by theinvention composition comprising an interpenetrating network of resins,separately curable, and under widely different conditions, acting torestrain one another for convenience and neatness of use, dependent onthe sequence of resin cure.

BACKGROUND

Interpenetrating network resin compositions are known. In one form thesecompositions have a first resin commingled with a second resin, eachbroadly maintaining its individual properties, such that the resultantof the blend is a combination of physical properties not afforded byeither resin individually.

SUMMARY OF THE INVENTION

It is an object of the invention to provide new applications ofinterpenetrating network resin compositions, ones in which one resinpossibly mechanically, blocks unwanted flow from a fiber reinforcementof the other resin, and new interpenetrating network compositions of afirst and second resin in which the first resin is a light cure resin,i.e. a resin which through the presence of suitably reactive andsuitably numerous reaction sites on the resin molecules and the presenceas needed of catalytic agents will react into high molecular weightpolymer upon exposure to light. The second resin is a thermosettingresin. In the invention systems the interpenetrating network uniquelyfunctions to support the thermosetting resin in place for cure by aninitial cure of the light cure resin, and the thermosetting resinuniquely supports the light cure resin in place for cure, depending onthe sequence of cure of the respective resins.

It is a specific object to provide for autobody component repair inaccordance with the invention in which a pre-preg of a fiberreinforcement impregnated with an interpenetrating network of light cureresin and thermosetting resin is placed and shaped with thethermosetting resin cured, the light cure resin is then cured in amatter of seconds or minutes, depending on composition and/or lightenergy applied, and serves to hold the pre-preg in place and in shapefor addition of body filler and finishing operations. It is anotherspecific object to provide for electronic assembly manufacture inaccordance with the invention in which a pre-preg of a fiberreinforcement impregnated with an interpenetrating network of light cureresin and thermosetting resin is interposed between opposed electroniccomponents with the light cure resin cured, the thermosetting resin isthen cured in a matter of seconds or minutes, depending on compositionand/or thermal energy applied, and serves to bond the componentstogether.

It is a further object to provide an invention which is broadlyapplicable to formation of end-use or intermediate structures of highlyvariable form in which the convenience and speed of light cure isdesirable, but in which the properties of conventional thermosettingresins is likewise desirable, in a sequence of light cure first andthermosetting resin cure second, or vice-versa, to methods of repair andmolding in which these characteristics of flexibility of result, speedand permanence are valued.

These and other objects of the invention to become apparent hereinafterare realized in accordance with the invention in the compositioncomprising an interpenetrating network of first and second resins, thefirst resin comprising a light curable resin, the second resincomprising a thermosetting resin.

The invention further includes the foregoing composition in combinationwith reinforcing fiber, and/or a filler, preferably a filler which islight transmitting sufficiently to permit cure of the light curableresin. Typically, the light cure resin and the thermosetting resin areeach present in amounts from 5 to 95 parts by weight per 100 parts byweight of said composition, in general the amount of each resin used issuch as will afford the short term or long term strength required in theapplication at hand, and/or block flow of the uncured resin when oneresin is first cured and it is desired to control flow of the otherresin until cure can be effected in the application.

Typical invention compositions will be combined with from 10 to 500parts by weight of reinforcing fiber per 100 parts by weight of saidcomposition, and/or from 5 to 500 parts by weight of filler per 100parts by weight of said composition.

In preferred modes, the composition is in combination with a reinforcingfiber, and the first and second resins are each impregnated into thereinforcing fiber, and one of the first and second resins is flowable,and the other of the first and second resins is at least of a molecularweight or sufficiently cured to be nonflowable and to retain the oneresin against flowing out from the reinforcing fiber. In this and likeembodiments the one flowable resin is the light curable resin, and saidother nonflowable resin is the thermosetting resin, or the one flowableresin is the thermosetting resin, and the other, nonflowable resin isthe light curable resin.

In the mentioned compositions, preferably, the light curable resincomprises an ethylenically reactive vinyl- or allyl-moiety containingmonomer, oligomer or polymer, and more particularly, the light curableresin comprises repeating units of acrylate, fumarate, maleate,unsaturated polyester resin, vinyl pyrollidone, vinyl pyridine, and/orbutadiene moieties, or repeating units of allyl alcohol and/or allylalcohol ester moieties. The thermosetting resin preferably comprisesrepeating urethane, epoxy, siloxane, phenolic and/or melamine linkages,and more preferably repeating urethane linkages, particularly where thelight curable resin comprises repeating acrylate moieties.

In certain preferred modes of the invention the mixed resin compositionis employed in combination with fiber reinforcement. The fiberreinforcement preferably comprises a fiberglass web, the fiberglass webbeing at least locally impregnated with said light curable andthermosetting resins. In this and like embodiment, there is furtherincluded a particulate filler, especially talc which does not inhibitlight cure of the light curable resin.

As noted, a particular advantage of the present invention is the abilityto have an uncured resin, albeit liquid, retained on the fiberreinforcement as though a viscous material by first curing one or theother of the resins, so as to support, as if occluding, the other resin,e.g. light curable acrylic or acrylate resin is cured sufficiently to benonflowing on said fiberglass web and retain uncured said thermosettingurethane resin from flowing from said fiberglass web.

In certain of such combinations, the light curable acrylate resin in itscured condition is sufficiently stiff to hold the fiberglass web in apredetermined configuration with the uncured urethane thermosettingresin distributed through the fiberglass web for subsequent cure.

Further in such combinations, the light curable acrylate resin in itscured condition comprises elongate strands threaded through saidthermosetting urethane resin impregnated in said fiberglass web inretaining relation against thermosetting urethane resin flow from saidfiberglass web.

Broadly, in the combination of the invention composition and fiberreinforcement, the thermosetting urethane resin is cured in aninterpenetrating network relation with said light curable acrylate resinon and through said fiberglass web. Accordingly the invention providesin combination a fiber reinforcement and a composition comprising alight curable resin cured into elongate strands extending through athermosetting resin impregnated into said fiber reinforcement inretaining relation against thermosetting resin flow from the fiberreinforcement.

In certain other embodiments, the thermosetting urethane resin issufficiently cured to be nonflowing on the fiberglass web and retainuncured the light curable acrylate resin from flowing from thefiberglass web. In such embodiments, typically, the thermosettingurethane resin in its cured condition is sufficiently stiff to hold thefiberglass web in a predetermined configuration with the uncuredacrylate light curable resin distributed through said fiberglass web forsubsequent cure. Further, the thermosetting resin in its cured conditioncomprises elongate strands threaded through the light curable acrylic oracrylate resin impregnated in said fiberglass web in retaining relationagainst light curable acrylic or acrylate resin flow from the fiberglassweb.

Broadly, the thermosetting urethane resin is cured in aninterpenetrating network relation with the light curable acrylate resinon and through said fiberglass web.

Accordingly, the invention provides in combination a fiber reinforcementand a composition comprising a thermosetting resin curable into elongatestrands extending through a light curable resin impregnated into a fiberreinforcement in retaining relation against light curable resin flowfrom the fiber reinforcement.

With particular reference to the mechanical arrangement of the resins,the invention provides a composition as just described in which thelight curable resin is intimately commingled with the thermosettingresin and so commingled is separately curable therefrom under lightenergy having no curing effect on the thermosetting resin.

In this and like embodiments, typically, the light curable resincomprises repeating acrylic or acrylate units and the thermosettingresin comprises repeating urethane linkages, the composition is usefullycombined with a fiber reinforcement, e.g. a fiber reinforcementcomprising fibers of glass, carbon, metal, synthetic organic polymer,cellulosic or protein material.

The fibers are advantageously arranged in a web, i.e. an elongated, orsquare or wide, generally flat, or round, or tubular array, such as aweb that forms or defines a fabric of woven or non-woven fibers. Thefiber reinforcement may comprise fabrics of different fibers, e.g. afiber reinforcement of fabrics which include glass cloth and syntheticorganic polymer cloth.

In a specific embodiment the invention comprises the structurecomprising a resin composition and a fiber reinforcement arranged in apredetermined configuration, the composition comprising aninterpenetrating network of first and second resins, the first resincomprising a light curable resin, the second resin comprising athermosetting resin. The composition may further comprise a filler,particularly a filler which is light transmitting sufficiently to permitcure of said light curable resin.

In such embodiments, typically the light curable resin and thethermosetting resin are each present in amounts from 5 to 95 parts byweight per 100 parts by weight of the composition, and/or thereinforcing fiber is present in an amount from 10 to 500 parts by weightper 100 parts by weight of the composition, and/or there is furtherpresent from 5 to 500 parts by weight of filler per 100 parts by weightof said composition, one of the light curable resin and thethermosetting resin is cured and the other uncured, the cured resinbeing distributed through the uncured resin in a manner to block flow ofthe uncured resin from the structure, e.g. the light curable resin isthe cured resin and the thermosetting resin the uncured resin.

The just described structure is useful in electronic assemblyapplications, e.g. the structure is adhered between opposed substratesblocking light access to the structure, whereby said structure isbondable to either or both of the substrates by cure of thethermosetting resin freely of further cure of the light curable resin.

Alternatively, the light curable resin is the uncured resin and thethermosetting resin is the cured resin, e.g. the structure is adhered toa substrate with the thermosetting resin and at least partially lightexposed, whereby said light curable resin is light curable in thesubstrate adhered condition of the structure.

In the embodiments discussed and others, typically, the thermosettingresin comprises repeating urethane, epoxy, siloxane, phenolic and/ormelamine linkages.

In a further aspect of the invention, there is provided a two-stagepre-preg structure comprising a fiber reinforcement impregnated with aninterpenetrating network of a light cure resin and a thermosetting resinwhich are independently curable. Typically, in this pre-preg structure,the fiber reinforcement comprises fibers of glass, carbon, metal,synthetic organic polymer, cellulosic or protein material, the lightcurable resin comprises repeating units of acrylate, fumarate, maleate,unsaturated polyester resin, vinyl pyrollidone, vinyl pyridine, allylalcohol, allyl alcohol ester, and/or butadiene moieties, and thethermosetting resin comprises repeating urethane, epoxy, siloxane,phenolic and/or melamine linkages.

In accordance with the invention, then, in the two-stage pre-pregstructure in which one of the light curable and thermosetting resins isinitially cured, the initially cured resin is distributively present inamounts holding the second of the resins in place on the fiberreinforcement for subsequent curable. The initially cured resin may bethe light curable resin or the thermosetting resin.

The invention further contemplates the provision of the pre-pregstructure and a substrate. In this connection in another aspect of theinvention, there is provided a method of building a multilayer elementincluding laminating a substrate with the pre-preg structure, typicallyincluding arranging the pre-preg structure in which the initially curedresin is cured against the surface portion of the substrate wherelamination is to take place, and curing the subsequently cured resin.

In yet another aspect, previously alluded to, the invention provides amethod of repair of a damaged vehicle body component, including removingthe damaged area, closing the resulting opening by extending thereacrossa pre-preg structure configured to form a slight recess, the pre-pregstructure comprising a light curable resin, a thermosetting resin and afiber reinforcement, the thermosetting resin being cured sufficiently tosupport the light curable resin on the fiber reinforcement againstflowing off the structure and sufficiently to render the structuresufficiently tacky to adhere to the body component around the opening,exposing the structure to light and after cure of the light curableresin filling the structure recess with body filler, and finishing therepair by smoothing the filler material.

In the aforementioned method, there may further be included shallowlychamfering the edge margin of the damaged area opening, and blending theedges of the pre-preg structure with the chamfered opening after cure ofthe light curable resin and before addition of body filler for a smoothtransition between the opening edge margin and the pre-preg structure.

Accordingly, the invention provides in this aspect, a repaired autobodycomponent comprising an autobody component having an openingcircumscribing a damaged area, a pre-preg structure extended across saidopening and slightly recessed, the pre-preg comprising a light curableresin, a thermosetting resin pre-cured to support the light curableresin on the fiber reinforcement, body filler supported on the pre-pregsubsequent to light cure of the light curable resin, the pre-pregstructure and filler being blended into the autobody component.

In a second major aspect, the invention provides a method of fabricatingelectronic assemblies including juxtaposing first and second componentsof an electronic assembly to be bonded together, interposing betweensaid components a cut-to-fit pre-preg structure comprising a fiberreinforcement impregnated with an interpenetrating network of a lightcurable resin and a thermosetting resin which are independently curable,the light curable resin being cured to retain the uncured thermosettingresin against flowing from the fiber reinforcement, and curing thethermosetting resin in situ between the components in componentco-bonding relation.

In this aspect of the invention, then there is provided an electronicassembly comprising first and second electronic components, andinterposed between the components in bonding relation a cut-to-fitpre-preg structure comprising a fiber reinforcement impregnated with aninterpenetrating network of a light curable resin and a separately curedthermosetting resin.

In still another aspect, the invention provides the method of moldingmoldable material into a desired shape, including out of lightconforming a fiber reinforced composition of uncurable light curableresin into a mold form having the reverse of the desired shape, curingthe light curable resin to maintain the reverse shape, and thereaftermolding the moldable material on the fiber reinforced composition in thedesired shape.

In accordance with this method, there is also included incorporating athermosetting resin into the light curable resin in an interpenetratingnetwork in the fiber reinforced composition, and curing thethermosetting resin to retain the light curable resin from flowing fromthe fiber reinforcement, thereupon molding the moldable material intothe desired shape and thereafter curing the light curable resin.

In another aspect, the invention provides for achieving the mentionedinterpenetrating network of resins, disposed as elongated strands, themethod of forming an interpenetrating network of separately curablelight curable resin and thermosetting resin including simultaneouslydriving each resin from separate containers through a common mixing zonehaving a series of baffles that alternately mix and divide the resins,and expressing the resins from the zone as intertwined elongatedstrands. More particularly, the method includes also driving the lightcurable and thermosetting resins reagents toward the common mixing zone,separately, to the common mixing zone, and commingling the respectivereagents to form the resins within the zone. In this last as in previousmethods, there is further included impregnating a fiber reinforcementwith the expressed resins.

The method of impregnating a fiber reinforcement with aninterpenetrating network of at least two resins, according to thisembodiment of the invention, includes separately simultaneously drivingthe resin reagents from respective containers through a common mixingzone which intimately commingles the reagents and expresses them fromthe zone in a pattern of elongated strands, depositing the expressedstrands onto a fiber reinforcement, and impregnating the fiberreinforcement therewith.

This method further contemplates selecting a light curable resin as oneresin and a thermosetting resin as a second resin, first combiningcertain of the light curable resin reagents with certain of thethermosetting resin reagents and the balance of the light cure resinreagents with the balance of the thermosetting resin reagents, andthereafter combining both sets of reagents in the common mixing zone toform the respective resins for expression from the zone.

In the just noted method, too, there is included, the resins beingfluid, sequentially reacting the resins to higher molecular weight so asto render the first reacted resin insufficiently fluid to flow from thefiber reinforcement, and blocking flow out of the fiber reinforcement ofthe second-to-be-reacted resin with the first reacted resin.

The invention is illustrated by the following Examples in which allparts are by weight.

EXAMPLE 1

Preparation Of The Light Curable Resin: The following were weighed intoa vessel: 40.0 parts of bisphenoldigylcidylether dimethacrylate(dimethacrylate ester of 400 molecular weight polyethyleneglycol); 2.5parts of diethylaminoethylacrylate and 0.2 parts of camphorquinone and10 parts of flame retardant Antiblaze 100 (Albright and Wilson). Theresin base was thoroughly mixed under low intensity red light at 25degrees F. Ten parts of particulate filler comprising fumed silica wereadded and thoroughly blended into the mixture. Then 7.5 parts of asecond particulate filler comprising talc were added and thoroughlyblended into the mixture. The mixture was degassed to 10 millimeters ofmercury and then packaged in sealed cartridges.

Preparation Of The Pre-Preg Structure: A pre-preg structure was preparedby impregnating a 4" by 10" multilayered layered strip consisting of toplayer comprising adhesive nylon mesh of 4 mil thickness, a firstintermediate layer comprising fiberglass mat of 16 mil thickness, asecond intermediate layer comprising adhesive nylon mesh of 4 milthickness and a bottom layer comprising fiberglass mat of 16 milthickness. Thirty-five grams of the light curable resin prepared abovewas applied from the cartridge uniformly across the strip upper surface.Oversize layers of polyethylene release film were used to protect thetop and bottom surfaces of the strip. The resin bearing multilayer stripwas then placed between squeeze rollers and the resin was thoroughlyincorporated into the several layers, and thusly impregnated into allthe interstices of the nylon mesh and glass mat. The resultantimpregnated multilayer assembly defines a typical pre-preg structureaccording to the invention. The pre-preg structure was then placed in anon-light-transmitting plastic (or metal foil) pouch to keep the lightcure resin stable and uncured.

Preparation Of The Laminate With Pre-Preg Structure: The just preparedpre-preg structure can be readily shaped or simply formed into diverseconfigurations, suitably after lamination to another material. Forexample, a highly useful laminate is prepared by pressing the pre-pregstructure against a fiberglass web, possibly containing a thermosettingresin impregnant, e.g. using a roller. In practice, it has been foundthat such a laminate will remain uncured for hours, allowing a greatamount of working time so as to precisely shape the laminate, even inindirect sun, or fluorescent or incandescent light at levels experiencedin shop areas. Upon being exposed to direct sunlight, however, thepre-preg structure bonds and curables to the fiberglass web, forming arigid structure after 5 minutes.

EXAMPLE 2

Preparation Of The Light Curable Resin Reagent Mixtures I AndThermosetting Resin: 19.5 parts of a liquified monomer ofdiphenylmethane diisocyanate (Mobay Chemical Mondur CD), was combined ina suitable vessel with 5.5 parts of water-free castor oil, 74.7 parts ofthe dimethacrylate ester of 400 molecular weight polyethyleneglycol and0.3 parts of camphorquinone. The mixture was heated to 160 F. for 1 hourunder nitrogen. The product was a light curable resin with thethermosetting urethane precursor resin therein. An aliquot portion ofthe resin was packaged under dry nitrogen.

Preparation Of The Light Cure Resin Reagent Mixture II and ThermosettingResin: 16 parts of a 6000 m.w. polyoxypropylene ether polyol triol, 5.2parts of ethylenediaminetetrapropoxylate, 3 parts of m-xylenediamine,0.25 parts of organo bismuth naphthenate, 47 parts ofbisphenoldiglycidylether dimethacrylate, 10.2 parts of thedimethacrylate ester of 400 m.w. polyethylene glycol, 5 parts ofdiethylaminoethylacrylate and 12 parts of Antiblaze 100 (Albright andWilson). The mixture was heated to 220 F. and degassed at 10 mm of Hgpressure and packaged.

Preparation Of The Pre-Preg: The Reagent Mixtures I and II and III weredispensed onto a mat/mesh assembly like that described in Example 1 fromcartridges loaded with the respective resin reagent mixtures, andcoupled to a common static mixer having a baffle system whichalternately divides and blends the resin reagents in an intimate mixingmanner, achieving an intimate blend in which the resins reagents arecommingled and striated into elongated strands which twist and turnthrough one another, effecting the interpenetrating network. Theresulting resins were squeeze rolled into the mat/mesh assembly as inExample 1. The thermosetting resin was cured leaving the light curableresin uncurable. The light curable resin did not flow from the fiberreinforcement of the mat/mesh combination. The resultant pre-preg wasplaced in a black pouch for protection against light and prematurecurable of the pre-preg/light curable resin.

Preparation Of The B-Stage Laminate: The foregoing pre-preg waslaminated to a rigid fiberglass and resin panel, simulative of asurfboard, by removing the pre-preg from the protective black pouch,separating the lower polyethylene release film, which left nearly allthe resins in place and laying the pre-preg, exposed resin side downonto the panel and in full contact therewith. The laminate was placed indirect sunlight. Within 5 minutes, the laminate cured, bonded and formeda rigid reinforcement against the fiberglass panel by the cure of thelight cure resin. It is characteristic of the inventions structures inthis aspect that the pre-preg can be formed and bonded in place usingonly the light cure resin, the thermosetting resin having been earliercured.

Alternatively, the invention affords quick conversion of the pre-preginto a immovable form or configuration, to be permanently converted uponfinal cure of the thermosetting resin, by cure of the light cure resin,and thereafter cure of the thermosetting resin.

EXAMPLE 3

Modification Of Light Curable Resin For Low Light Cure: There was addedto Example 2, Side B, 100 parts, 0.5 parts of titanocene catalystcomprising Bis(N⁵ -2,4-cyclopentadien-1-yl),Bis(2.6-difluoro-3-(1H-pyrrol-1-yl) phenyl) titanium, available fromCiba Geigy under the trade name CGI (Irgacure) 784, and the mixtureblended thoroughly. The laminating steps of Example 2 were repeated butinstead of direct sunlight the indoor fluorescent light was used. Theresult was the same, a structural laminate.

EXAMPLE 4

Preparation Of The Light Curable Resin Reagent Mixture I AndThermosetting Resin: 20.4 parts of dicyclohexane diisocyanate and 29.6parts of a 6000 m.w. polyoxypropylene ether polyol triol were mixed in areaction vessel. The mixture was heated to 320 F. for 30 minutes andthen cooled to 200 F. A fifty gram quantity of the dimethacrylate esterof 400 molecular weight polyethylene glycol was added to the prepolymeralong with 0.2 parts of camphorquinone. The mixture was maintained at200 F. and vacuumed at 10 millimeters of pressure, cooled to roomtemperature and packaged under vacuum.

Preparation Of The Light Cure Resin Reagent Mixtures II AndThermosetting Resin: 39 parts of a 6000 m.w. polyoxypropylene ethertriol polyol, 10 parts of ethylenediamine tetrapropoxylate, 1 part ofbismuth napthenate, 33.3 parts of bisphenoldiglycidyletherdimethacrylate, 3.4 parts of diethylaminoethylacrylate, and 8.3 parts ofa fire retardant (Antiblaze 100 from Albright and Wilson) was mixed in asecond reaction vessel. The mixture was heated to 220 F. and vacuumed at10 millimeters of Hg.

Preparation Of The Pre-Preg-B-Stage: The I and II mixtures were mixedthoroughly and placed in respective cartridges. The combined mixtureswere dispensed from the cartridges onto the a mat/mesh assembly as inExample 1 and protected by release film was squeezed between two rollersto create uniform distribution of the resin in the pre-preg. Thepre-preg was then shaped and light-curable under sunlight. The resultwas a shaped matrix which contained, supported against flow from thereinforcement, the unreacted urethane thermosetting materials.

Pre-Preg Reaction To C-Stage. The shaped matrix just prepared was curedto its final cure point (C-Stage) by placing the matrix in the oven at200 F. for 24 hours.

The foregoing composition can be filled with up to 25 parts by weight ofa particulate filler such as talc with like results, at a lower cost.

EXAMPLE 5

Laminate Adhesive In Circuit Board Production: A pre-preg is prepared asin Example 4, but before the final cure the matrix is die-cut to a shapeuseful in bonding heat sinks to printed circuit boards. The light cureresin is reacted under appropriate light. The cured light cure resinbonded pre-preg is bonded to the fiber-reinforced polymer circuit boardsubstrate by then curing the thermosetting resin in contact with thesubstrate. After positioning the heat sink element atop the circuitboard substrate the thermosetting resin is cured, permanently bondingthe heat sink element to the board. The matrix proves uniquelyadvantageous in reducing warpage in thermal stress situations below thatof other laminate adhesives.

EXAMPLE 6

Auto body components are repairable more easily and quickly with thepre-preg structures of the present invention. In a typical repair of anautobody component, the damaged area is cut away, backing is placedacross the rear face of the cut away area for supporting the putty likerepair material. Before this invention, the support backing had to beinstalled behind the cut away area, a difficult proposition given thesize of the cut away area and the awkwardness of reaching into reconditelocations.

While the pre-preg structures of this invention can be used in the oldstyle of repair, and with advantages in that the pre-preg structure isflexible for insertion and can then be rigidified by simple lightexposure, to support the repair paste, the uniquely responsiveproperties of the invention structures open new avenues of repair whichare highly advantageous.

Thus, in accordance with the invention, the damaged area is cut-away asbefore, but the opening edges are chamfered at a substantial angle, e.g.45 degrees or more, to suitably provide an inch of slope in a 1/4 inchthick panel. Rather than putting the support structure behind theopening, in this aspect of the invention the pre-preg structure,thermosetting resin-cured to hold the uncured light cure resin in placeand to give the pre-preg a clean handling feel, is fitted to theopening, using the chamfering to keep the pre-preg from extending abovethe plane of the component surface. The pre-preg structure is then lightcured, as by moving the vehicle outside into the sunshine, bonding thepre-preg in place. The pre-preg structure can be bellied back toaccommodate the repair paste and repair proceeds as with other repairschemes.

It will be evident from the foregoing Examples that the inventionbroadly provides a composition comprising in a preferred embodiment aninterpenetrating network of first and second resins, the first resincomprising a light cure resin and the second resin comprising athermosetting resin, reinforcing fiber and a filler. The relativeproportions of these resins is not narrowly critical with each resinbeing suitably present in weight amounts from 5 to 95 parts per 100parts of the resin content of the composition. Obviously the specificproperties of the composition will vary with the relative amounts ofeach resin. The term light cure resin herein refers to a resin whichwill crosslink or cure under visible or invisible light with or withoutthe added presence of a catalyst. In general, the light cure is rapidlyeffected as an advantage of the invention. Light cure polymers arewidely known, in the dental field for example.

Thermosetting resins are those which crosslink or cure in response tothermal energy including elevated or ambient thermal energy as well asspecific heat ranges peculiar to given resins. Typically, the curingreaction in these polymers is an addition reaction. The thermosettingresins are generally immune to cure under light and this enables atwo-step curable cycle with the light cure being effected without cureof the thermal cure resin as shown above.

Specific chemical systems useful as the light cure resin include resinscomprising an ethylenically reactive vinyl- or allyl-moiety containingmonomer, oligomer or polymer, such as and typically those resins whichcomprise repeating units of acrylic or acrylate, fumarate, maleate,unsaturated polyester resin, vinyl pyrollidone, vinyl pyridine, and/orbutadiene moieties, or repeating units of allyl alcohol and/or allylalcohol ester moieties.

Specific chemical systems useful as the thermosetting resin includeresins comprising repeating urethane, epoxy, siloxane, phenolic and/ormelamine linkages.

The reinforcing fiber content of the invention compositions andstructures will generally range between 10 to 500 parts by weight ofreinforcing fiber per 100 parts by weight of the resin composition.Suitable reinforcement, as earlier noted, includes fiber reinforcementthat comprises fibers of glass, carbon, metal, synthetic organicpolymer, e.g. aramide fibers, cellulosic, e.g. rayon and wood fibers, orprotein material such as wool.

While the reinforcing fibers can be randomly distributed and of the sameor different lengths, arranged paraxial or transversely, or both, it ispreferred for ease of handling that the fibers be arranged in a web. Thefiber web may be a fabric of woven or non-woven fibers, and layers ofdifferent fabrics of fibers can be used as previously set forth.

The objects of the invention are thus met, including provision of newapplications of interpenetrating network resin compositions, ones inwhich one resin possibly mechanically, blocks unwanted flow from a fiberreinforcement of the other resin, and new interpenetrating networkcompositions of a first and second resin in which the first resin is alight cure resin, i.e. a resin which through the presence of suitablyreactive and suitably numerous reaction sites on the resin molecules andthe presence as needed of catalytic agents will react into highmolecular weight polymer upon exposure to light. The second resin is athermosetting resin. Also provided is an autobody component repair inwhich a pre-preg of a fiber reinforcement impregnated with aninterpenetrating network of light cure resin and thermosetting resin isplaced and shaped with the thermosetting resin cured, the light cureresin is then cured in a matter of seconds or minutes, depending oncomposition and/or light energy applied, and serves to hold the pre-pregin place and in shape for addition of body filler and finishingoperations. Also provided is a method of electronic assembly manufacturein accordance with the invention in which a pre-preg of a fiberreinforcement impregnated with an interpenetrating network of light cureresin and thermosetting resin is interposed between opposed electroniccomponents with the light cure resin cured, the thermosetting resin isthen cured in a matter of seconds or minutes, depending on compositionand/or thermal energy applied, and serves to bond the componentstogether. In addition, there are provided method and means of formationof end-use or intermediate structures of highly variable form in whichthe convenience and speed of light cure is desirable, but in which theproperties of conventional thermosetting resins is likewise desirable,in a sequence of light cure first and thermosetting resin cure second,or vice-versa, to methods of repair and molding in which thesecharacteristics of flexibility of result, speed and permanence arevalued.

We claim:
 1. Composition for interpenetrating network comprising a firstreagent and a second reagent, said first reagent comprising a lightcurable resin of an ethylenically reactive vinyl-, or allyl-moietycontaining monomer mixed with urethane polymer formers comprisingdiphenyl methane diisocyanate or dicyclohexane diisocyanate; said secondreagent comprising a light curable resin of an ethylenically reactivevinyl-, or allyl-moiety containing monomer, oligomer or polymer and apolyol forming a urethane polymer with said diisocyanates; incombination with a filler for said composition in at least one of saidfirst and second reagents, said composition and said filler beingfurther combined with fiber reinforcement and a catalyst for the lightcure of said light curable resin under conditions under which said lightcurable resins are not reactive and remain flowable and said urethanepolymer forming diisocyanates are reactive with said polyol to formurethane polymer which is sufficiently cured to be nonflowable and toretain said light curable resins in place against flowing from saidreinforcing fiber.
 2. Combination according to claim 1, in which saidfiller is light transmitting sufficiently to permit curable of saidlight curable resins.
 3. Combination according to claim 1, in which saidlight curable resins and said urethane polymer reaction product of saiddiisocyanates and polyol are each present in amounts from 5 to 95 partsby weight per 100 parts by weight of said composition.
 4. Combinationaccording to claim 3, in which said filler is particulate and is presentin an amount from 5 to 500 parts by weight of filler per 100 parts byweight of said composition.
 5. Combination according to claim 3, inwhich said reinforcing fiber is present in an amount from 10 to 500parts by weight per 100 parts by weight of said composition. 6.Combination according to claim 5, which said filler is particulate andis present in an amount from 5 to 500 parts by weight of filler per 100parts by weight of said composition.
 7. Combination according to claim3, in which said light curable resins and urethane polymer are eachreinforced said reinforcing fiber, said combination being flexiblyformable until said light curable resin is cured.
 8. Combinationaccording to claim 1, in which said fiber reinforcement comprises fibersof glass, carbon, metal, synthetic organic polymer, cellulosic orprotein material.
 9. Combination according to claim 8, in which saidlight curable resin comprises repeating units of allyl and/or allylalcohol ester moieties.
 10. Combination according to claim 1, in whicheach said light curable resin comprises repeating units of acrylic oracrylate, fumarate, maleate, unsaturated polyester resin, vinylpyrollidone, vinyl pyridine, and/or butadiene moieties.
 11. Combinationaccording to claim 1, in which said filler comprises talc or silica. 12.Combination according to claim 1, in which said fiber reinforcementcomprises fibers of glass, metal, synthetic organic polymer, cellulosicor protein material arranged in a web.
 13. Combination according toclaim 12, in which said fiber reinforcement comprises fiberglass web.14. Combination according to claim 13, in which said filler comprisestalc or silica.
 15. Combination according to claim 14, in which saidfiber reinforcement comprises a fiberglass web.
 16. Combinationaccording to claim 1, light cure catalyst comprises a titanocene. 17.Combination according to claim 1, in which said light cure catalystcomprises Bis(N5-2,4-cyclopentadien-1-yl),Bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium.